Abstract Background Investigations of participant retention in longitudinal health and medical research, document strategies that work best but overlook social marketing’s capacity to influence participant retention. After applying the social marketing framework: the idea that determining what longitudinal participants ‘buy’ (product), at what cost (price), in what location (place) and through which communication channels (promotion), this paper aims to inform and enhance retention efforts. Methods This qualitative study was conducted through in-depth interviews with participants...